The present invention relates generally to scroll type compressors and more specifically to scroll type compressors incorporating a one-way clutch operative to prevent reverse movement of the orbiting scroll member.
Scroll type machines are becoming more and more popular for use as compressors in both refrigeration as well as air conditioning applications due primarily to their capability for extremely efficient operation. Generally, these machines incorporate a pair of intermeshed spiral wraps, one of which is caused to orbit relative to the other so as to define one or more moving chambers which progressively decrease in size as they travel from an outer suction port toward a center discharge port. An electric motor is provided which operates to drive the orbiting scroll member via a suitable drive shaft. Because scroll compressors depend upon a seal created between opposed flank surfaces of the wraps to define successive chambers for compression, suction and discharge valves are generally not required. However, when such compressors are shut down, either intentionally as a result of the demand being satisfied or unintentionally as a result of a power interruption, there is a strong tendency for the pressurized chambers and/or backflow of compressed gas from the discharge chamber to effect a reverse orbital movement of the orbiting scroll member and associated drive shaft. This reverse movement often generates objectionable noise or rumble. Further, in machines employing a single phase drive motor, it is possible for the compressor to begin running in the reverse direction should a momentary power failure be experienced. This reverse operation may result in overheating of the compressor and/or other damage to the apparatus. Additionally, in some situations, such as a blocked condenser fan, it is possible for the discharge pressure to increase sufficiently to stall the drive motor and effect a reverse rotation thereof. As the orbiting scroll rotates in the reverse direction, the discharge pressure will decrease to a point where the motor again is able to overcome this pressure head and rotate the scroll member in the "forward" direction. However, the discharge pressure will now increase to a point where the cycle is repeated. Such cycling may also result in damage to the compressor and/or associated apparatus.
The present invention overcomes these problems by incorporating a one-way clutch coupled to the drive shaft which effectively prevents the orbiting scroll member from moving in a reverse direction thereby eliminating the objectionable noise generated upon shut down of the compressor. Further, this one-way clutch operates to resist damage to the motor and/or compressor resulting from a reversing of single phase motors as well as resisting the cyclical reversing resulting from a blocked or failed condenser fan. In this latter situation, the motor may still stall but the one-way clutch will hold it against reverse rotation until such time as the thermally actuated motor protector is tripped, thus avoiding potential damage thereto.
In one embodiment, the one way clutch is disposed within a recess provided in the lower bearing housing axially adjacent the bearing surfaces. In another embodiment, the one-way clutch serves the dual function of also providing the radial bearing support for the rotating drive shaft.
Additional advantages and features of the present invention will become apparent from the subsequent description and the appended claims taken in conjunction with the accompanying drawings.